Keywords

Sleep apnoea

Abbreviations

AHI: apnoea-hypopnoea index

DISE: drug-induced sleep endoscopy

EBV: Ebstein-Barr virus

ENT: ear, nose and throat

OSAS: obstructive sleep apnoea syndrome

PAP: positive airway pressure

Take-home messages

1. OSAS is underdiagnosed but common: OSAS affects a significant portion of the population, yet many cases go undetected, especially in individuals with subtle or atypical symptoms.
2. Daytime symptoms matter: persistent daytime sleepiness, cognitive issues, or snoring (especially with observed apnoeas) should raise suspicion of OSAS and prompt further evaluation.
3. Multifactorial causes require multidisciplinary care: effective diagnosis and treatment often involve collaboration between ENT specialists, pneumologists, neurologists, and other healthcare providers.
4. Polysomnography is the gold standard: comprehensive sleep studies, particularly in-lab polysomnography, are critical for accurate diagnosis and treatment planning, but there is space for compromise in the use of slightly less accurate tests with the advantages of easier access and feasibility.
5. Treatment is highly individualised: management may include lifestyle changes, PAP therapy, oral devices, and/or surgery, with interventions tailored to anatomical findings, severity of symptoms. and patient compliance.

Patient-oriented messages

If you often feel tired during the day, snore loudly, or wake up feeling unrefreshed, you might be experiencing signs of obstructive sleep apnoea syndrome (OSAS). This common but often overlooked condition can seriously affect your health and quality of life, even increasing the risk of high blood pressure, heart rhythm disorders, heart failure, and stroke. Fortunately, OSAS is treatable. Diagnosis usually involves a sleep study, and treatments can range from simple lifestyle changes to using breathing devices at night. Don’t ignore the signs: talk to your doctor. Addressing sleep apnoea early can help you sleep better, feel more energetic, and reduce your risk of long-term health problems.

Introduction

Sleep disorders are a very frequent cause of complaints reported by patients in everyday clinical practice. Several specialists and professional figures may contribute to the diagnostic and therapeutic work-up. ENT specialists may be decisive in a subgroup of pathologies mainly determined by the obstruction of airflow in the upper respiratory tract, thanks to the possibility of conducting a thorough physical exam, completed by fibre optic exploration of the upper aero-digestive tract, the prescription of an appropriate sleep test, and the performance of some types of surgery addressed to solve certain specific causes of these conditions. That said, this brief review will concentrate on obstructive sleep apnoea syndrome (OSAS), a clinical syndrome determined by the collapse of the upper airway during sleep and the consequent obstructive apnoeas/hypopnoeas followed by micro-awakenings (arousals). It is estimated that OSAS prevalence varies from 14 to 55% depending on age subgroup across Europe; many of the people suffering from this condition are diagnosed late or not at all.

Symptoms

Per its definition, OSAS is characterised by episodes of apnoea and/or hypopnoea during sleep [1,2]. These episodes occur mainly during the rapid eye movement (REM) phase - whose presence and stability are essential for effective sleep -resulting in sleep fragmentation and consequent tiredness during the day. Namely, the conditions characterising OSAS are:

• Snoring: the production of respiratory noise during sleep due to the vibration of the soft tissues of the oropharynx, facilitated mainly by the supine position and muscle hypotonia (typical of the REM phase): the upper airway walls collapse, partially obstructing the respiratory space. But while the majority of OSAS patients snore, only a fraction of snorers is actually affected by OSAS. When possible, it is important to interview the patient’s partner in order to gain more insights on the possible accompanying sounds, such as apnoeic periods followed by a rough restarting of snoring and, possibly, gasping.
• Episodes of hypopnoea: in the adult, they are defined by a reduction in respiratory flow of more than 30%, along with a decrease in oxygen saturation (hypoxaemia) of at least 4% compared to baseline.
• Episodes of apnoea: in the adult, when respiratory flow completely ceases for at least 10 seconds.

Snoring, hypopnoea, and apnoea are thus three progressively more severe manifestations within the same pathophysiological spectrum, based on the local obstruction of the upper airways.

In addition to nocturnal events (which are the defining symptoms), daytime symptoms are usually associated: sleepiness is vastly present and can vary from an innocuous “dozing off” during calm situations (e.g., sitting in a quiet place after a meal) to more dangerous situations (OSAS is strongly associated with car accidents [3]). Codified syndromes like narcolepsy, behavioural and cognitive disorders, and parallel symptoms like headache, gastro-oesophageal reflux, enuresis, and impotence may appear if the condition is chronic.

Given the variety of manifestations included in this syndrome, differential diagnosis (DDx) may be challenging, especially in atypical presentation:

• Narcolepsy: DDx may be especially difficult with type 2 narcolepsy (excessive daily sleepiness but absence of cataplexy).
• Restless leg syndrome: irresistible urge to move the legs; classified as a sleep disorder because it manifests especially during rest or when the patient attempts to sleep, causing disruption of sleep and daytime sleepiness.
• Central sleep apnoea: broad spectrum of conditions caused by dysfunctions of the medullary and pontine respiratory centres, leading to impaired regulation of respiratory drive.
• Snoring in absence of OSAS (primary snoring): almost every OSAS patient is a snorer, but not every snorer has OSAS.
• Gastro-oesophageal reflux disease (GERD): can produce nocturnal dyspnoea and, sometimes, respiratory sounds.

The most important risk factors associated with OSAS are male sex (even though the risk for females post-menopause approaches that of males), age (incidence gradually increases over decades), craniofacial malformities (i.e., micrognathism, retrognathism) and, especially, obesity (as it leads to greater deposits of adipose tissue in the lateral pharyngeal spaces and to diaphragm elevation).

Pathophysiology

Typically, OSAS derives from the collapse of the pharyngeal walls during sleep due to the increase in negative endoluminal pressure exerted in the airway during inspiration. This is facilitated by sleep itself (especially during the REM phase, which causes hypotonia of the pharyngeal muscles) and by supine positions that cause backward displacement of the tongue and, theoretically, a redistribution of interstitial fluids in the passage from orthostatism to clinostatism).

The pharynx is the most frequent site of OSAS because it lacks a bony or cartilaginous framework. It collapses most easily at the velopharyngeal level (behind the soft palate) and at the retrolingual level, from the uvula to the epiglottis. On the other hand, the nasal tract and the larynx, thanks to the substantial rigidity of their walls, are not sites of OSAS.

As explained, a narrow, crowded and/or collapsible upper airway is the main pathophysiological mechanism of OSAS. There are additional ones that can, alone or concurrently, cause peripheral sleep apnoea:

• Poor muscle responsiveness: pharyngeal wall muscles may be less responsive to the neurological pathway triggered by hypoxaemia and hypercapnia, resulting in a later contraction and a longer apnoea/hypopnoea interval.
• Low arousal threshold: a neurological mechanism in which the patient wakes up before reaching usual triggering levels of hypoxaemia, leading to possible instability in the nocturnal respiratory pattern
• High loop gain: another neurological mechanism in which ventilatory response to pO2 changes is abruptly accentuated, leading again to instability in the nocturnal respiratory pattern.

These last mechanisms are usually less responsive to a surgical approach; in addition, common sleep testing does not easily differentiate among them. Referral to a neurologist in order to look for these may be suggested in the presence of unusual patterns observed during sleep testing or in case of failure of prescribed therapy [4].

Complications

OSAS should never be underestimated, and patients presenting a compatible phenotype complaining about snoring or daytime tiredness should not be disregarded. Prevalence of OSAS is high in the general population, and the syndrome is connected with a variety of possible complications:

• Increased risk of motor vehicle accidents due to daytime sleepiness,
• Neuropsychiatric dysfunctions (consequences of sleep deprivation), irritability, etc.,
• Cardiovascular and cerebrovascular morbidity,
• Group 3 pulmonary hypertension,
• Metabolic syndrome (indirectly, as some risk factors are shared, but also directly via an increase of glucose and triglyceride levels),
• Non-alcoholic fatty liver disease (NAFLD).

Cardiovascular morbidity may be difficult to assess due to the confounding compresence of obesity in these patients. There is a well-established correlation of OSAS with acute events (e.g., myocardial infarction, acute coronary syndrome, stroke), hypertension, cardiac arrhythmias (atrial fibrillation [5]), heart failure [6], sudden cardiac death, pulmonary hypertension [7], and venous thromboembolism.

Diagnosis

Clinical suspicion derives from the complaint of the above-mentioned symptoms (daytime sleepiness, snoring, episodes of apnoea) especially in the presence of risk factors (obesity, male sex, older age). Particular attention must be paid to associated conditions, especially cardiovascular ones.

While these elements could be sufficient to warrant further evaluations of a patient, some screening tools can be useful (such as the STOP-BANG questionnaire and the Epworth sleepiness scale [8]) and are detailed in the article from Drs. Mads Hashiba & Morten Lamberts available in this series on CardioPractice.

Polysomnography (PSG) is the gold-standard diagnostic test for OSAS. This test is best performed in a dedicated sleep laboratory with a neurophysiology technician monitoring it and consists of a complete set of registration channels:

• Electroencephalogram (EEG) and electrooculogram (for sleep phase analysis),
• Facial muscle electromyography,
• Nasal and oral airflow,
• Thoracic and abdominal respiratory effort using plethysmographic bands,
• Peripheral oxygen saturation and heart rate,
• Electrocardiogram (EKG),
• Body position/limb movements via accelerometer,
• Snoring via audio recording.

A more advanced examination could also include video registration. In-lab PSG, while being the gold standard for diagnosis, is actually suggested especially for patients suspected to suffer from central or mixed conditions (compresence of central and peripheral sleep disorders) and for high-responsibility workers suspected of OSAS (truck or bus drivers, pilots, etc.); we report that in Italy a diagnosis of OSAS could put the patient at risk of losing his/her driving license if appropriate treatment is not followed.

In-lab PSG testing can be executed in the form of full-night studies or split-night studies: the first has an exclusive and maximised diagnostic value, while the latter has a second part in which positive airway pressure (PAP) therapy is applied and titrated.

For a less burdensome alternative, polygraphy (without EEG) can also be performed at home, recording airflow, respiratory effort, oxygen saturation, heart rate, body position, limb movement, and snoring. If there is no clinical suspicion of neurological conditions (that would impose registration of EEG), this is the usually suggested and most common testing method.

Consequently, at-home testing can be considered in conditions where OSAS (that is, a pure peripheral disorder) is the main and most probable diagnosis. A clear example of this is children with typical symptoms of objectivated adenotonsillar hypertrophy. A negative home test in a situation where the clinician strongly suspects OSAS should prompt the execution of a PSG.

An even more comfortable test setting is 4-channel cardiorespiratory monitoring comprising pulse oximetry, heart rate monitoring, thoracic band and one EKG derivation, that is allowed as at-home, first-level testing in children with clear suspicion of OSAS between 3 and 6 years of age. Some authors propose simple pulse oximetry in children. Obviously, the fewer the registration channels, the lower the accuracy.

Table 1. Main diagnostic criteria for OSAS (ICSD 3, 2014) [1].

PSG: polysomnography; RDI: respiratory disturbance index

The International Classification of Sleep Diseases (version 3, 2014, see Table 1) defines the diagnostic criteria for OSAS distinguishing adult and paediatric patients. The PSG (or similar test) parameter used for diagnosis in this classification is the respiratory disturbance index (RDI), which is obtained by fractioning respiratory effort-related arousals (RERAs) and time [1].

While diagnosing OSAS, sleep studies also help to classify its severity using the apnoea-hypopnoea index (AHI), measured as the number of events (including both apnoeas and hypopnoeas) per total sleep time in hours:

• AHI < 5: No OSAS,
• AHI 515 (with symptoms): Mild OSAS,
• AHI 15–30: Moderate OSAS,
• AHI > 30: Severe OSAS.

Otolaryngologists may study the local causes of OSAS; any mechanical obstruction to proper airflow in the cervicofacial region can determine or contribute to this condition. All pathologies that obstruct the nasal cavities (polyps, turbinate hypertrophy, septal deviation), the nasopharynx (adenoid hypertrophy in children, rare Epstein-Barr virus (EBV)-related malignancies in adults), the oropharynx (hypertrophy of tongue base, uvula, soft palate, palatine tonsils), the hypopharynx, and the larynx must be examined and appropriately treated if indicated. Many important factors can be easily assessed by simple oropharyngoscopy:

• Mallampati and Friedman scales (the latter, measured with the tongue inside the mouth in resting position, better predicts potential upper airway collapse) [9],
• Craniofacial morphology (micrognathism, retrognathism, etc.),
• Dental occlusion anomalies (angle classification),
• Tonsillar/adenotonsillar hypertrophy,
• Inclination of soft palate (Woodson classification: oblique, intermediate, or vertical),
• Visible morphological changes (macroglossia, etc.).

Endoscopy with flexible fibre optics provides an overview of the entire upper airway, from the nasal cavities to the larynx. During endoscopy it is possible to:

• Assess base-of-tongue hypertrophy according to Moore classification.
• Execute the Müller manoeuvre: serving as a simulation of what happens during sleep, it is performed in an upright position: the operator positions the endoscope at the oropharyngeal level, asks the patient to perform a complete exhalation, then closes the patient’s nostrils and requests a forced inhalation with a closed mouth. The resulting negative pressure in the upper airways causes collapse of the structures, which is observed twice — once at the retropalatal level and once at the retro-lingual level. The endoscopist should then describe the obstruction pattern (anteroposterior, lateral, or circular) and degree, according to this scale:
  • Grade I: 0–50% collapse,
  • Grade II: 50–75% collapse,
  • Grade III: over 75% collapse,
  • Grade IV: complete collapse.
• Explore thoroughly the rest of the upper respiratory tract in order to exclude potential causes of OSAS (malformations, malignancies, surgery or radiotherapy effects after treatment of local malignancies).

We will discuss another stage of the diagnostic pathway later: drug-induced sleep endoscopy (DISE), that is usually performed only after primary therapy with PAP has failed.

Finally, diagnostic imaging is useful for excluding secondary causes, OSAS, or concomitant factors (like nasal diseases).

OSAS in the paediatric age group

As explained before, OSAS in children is mainly due to adenotonsillary tissue hypertrophy [10]. This is quite frequent during the developing ages because of the hyperactivity of the lymphoid tissue constituting the Waldeyer ring (palatine tonsils, lingual tonsil, adenoid). As seen in Table 1, some symptoms and main diagnostic criteria are different from adults. It must be remembered that the definition of apnoea is also different: in children, we define an episode of apnoea as the absence of breathing for two consecutive respiratory acts. An episode of hypopnoea is defined as a reduction of ≥50% of airflow for two respiratory acts with either a reduction of ≥3% in SpO2 or a microarousal.

In children, proper management of OSAS is important to avoid developmental issues. Since childhood and adolescent obesity is becoming a health issue even in European countries, clinicians (including paediatricians working in the territory) should become more attentive to the relevance and impact of OSAS.

Treatment

Treatment is multidisciplinary and consists of a multi-step process; complex cases should be discussed in an appropriate multidisciplinary board, together with the ENT surgeon, the maxillofacial surgeon, the pneumologist, the dietologist, and eventually the neurologist.

Every patient may benefit from lifestyle modifications and should be instructed to implement them (weight loss, sleep posture changes, avoiding smoking, alcohol, and sedatives). We stress the importance of weight loss: a recent meta-analysis which reported that a 20% reduction of BMI resulted in a 57% reduction of AHI [11]. Weight loss should be pursued preferably via lifestyle intervention and, if this is not sufficient, with pharmacotherapy and/or bariatric surgery.

The supine position during sleep favours collapse of the oropharynx, to such a degree that polygraphy reports usually define, together with standard AHI, a supine AHI. A supine AHI greater than standard AHI indicates a sleep posture component that can be corrected with an immediate impact on sleep quality. Some wearable devices can help through mechanical or vibratory discouraging of the supine position during the night.

The most used and efficient treatment is positive airway pressure (PAP) ventilation, prescribed and managed by a pneumologist. It works by maintaining a higher intraluminal pressure that prevents the pharyngeal walls from collapsing [12]. There are different types of functioning:

• Continuous PAP (CPAP) provides continuous positive airway pressure, and requires titration of correct pressure values in a lab setting,
• Automatic PAP (APAP) dynamically adjusts pressure based on airflow, so it does not require titration,
• Bilevel PAP (BPAP) delivers different pressures for inhalation and exhalation, theoretically improving compliance.

Patients using PAP therapy must be included in a follow-up program: monitoring of sleep and sleepiness parameters, measurement of collateral positive effects (such as improvement of arterial hypertension [13]), management of collateral negative effects (xerostomia, facial skin irritation, nasal congestion, psychological impact). The patient needs to be constantly reminded of the benefits of using the device. As a matter of fact, PAP therapy fails especially in one scenario: when the patients cannot bear the discomfort generated by the device. Besides the problem of nonadherence or inadequate setting of the PAP therapy, this method might fail in cases where the underlying aetiology of the sleep apnoea was different from what was originally suggested.

If PAP therapy fails, or if the patient is not compliant, it is suggested to perform a drug-induced sleep endoscopy [14]. This consists of executing a fibre optic endoscopy of the upper airways while the patient is under the effect of a sedative drug administered by the anaesthesiologist in a safe environment (like the operating room). This way we can mimic quite faithfully a normal sleeping situation, highlighting site and degree of obstruction. Results are categorised through the VOTE classification [15] or the NOHL classification [16] (Table 2B). DISE is necessary before planning any other types of treatment (e.g., oral devices vs surgery).

Video 1. Sleep endoscopy.

Table 2A. VOTE classification during DISE [15].

(n/a: not applicable)

Table 2B. NOHL classification during DISE [16].

*Larynx subsite needs to be specified: a (supraglottic) or b (glottic).

Further treatment strategies may include mandibular advancement devices (MADs): oral devices designed to enlarge the oropharyngeal respiratory space by dislocating the mandible antero-inferiorly. They cannot be proposed in the presence of severe periodontal disease, scarcity or instability of dental elements, or temporo-mandibular joint dysfunction. Response to this treatment may be predicted during DISE by executing an anterior dislocation of the mandible, simulating its effect.

Regarding surgery, its success can be calculated in different ways: one of the most used defines a surgery as successful if AHI is at least halved and post-operative RDI is below 20 events/hour. This explains the fundamental aim of surgery: while it is not necessarily curative, it should at least improve the situation and compliance to PAP therapy. We stress the fact that surgery is always contraindicated if BMI is superior to 35 kg/m² (as is bariatric surgery as well). There are many options, evaluated and proposed by the ENT surgeon or the maxillofacial surgeon (whose surgeries will not be discussed here).

• Nasal surgeries like functional septoplasty, turbinoplasty, functional endoscopic sinus surgery, (FESS, executed for sinusitis with or without nasal polyps): a deviated septum, hypertrophy of the nasal turbinates, and/or other nasal-obstructing pathologies do not worsen OSAS, but they can make compliance to PAP therapy more difficult, because the patient needs higher pressure to produce a valid airstream in the airway. Therefore, surgical correction does not improve AHI significantly, but it can improve patients’ compliance to PAP therapy.
• Tonsillectomy: in the paediatric age (jointly with adenoidectomy) this intervention solves the majority of cases of OSAS; in the adult it could be proposed in case of severe hypertrophy of the palatine tonsils (grade IV).
• Expansion sphincter pharyngoplasty: after tonsillectomy, this technique consists in an enlargement of the oropharyngeal space by sectioning the palatopharyngeal muscle (the main component of the posterior tonsillar pillar). 

Video 2. Tonsiliectomy and pharyngoplasy.

• Barbed reposition pharyngoplasty: after tonsillectomy, this technique consists in advancing the position of the soft palate using submucosal sutures that push it anteriorly. Palatoplasty techniques are part of the greater group of uvulopalatoplasty (UPP) and may vary also according to the necessity of shortening the uvula.
• Transoral surgical reduction of the base of the tongue: preferably applicable in selected types of tongue base hypertrophy (triple L: low, localised, lymphatic).
• Epiglottoplasty: several variants exist; one of the most used is the epiglottis stiffening operation, which consists in a thermocautery of the glossoepiglottic valleculas (a mucosal area between the base of tongue and the lingual face of the epiglottis) in order to reduce posterior collapse of the epiglottis during inspiration.
• Tracheostomy: this is traditionally indicated as a last resort for severe refractory cases, but it is not used anymore.

Lastly, hypoglossal nerve stimulation is a procedure introduced in clinical practice in the last ten years. A stimulating device is surgically inserted near branches of the hypoglossal nerve; another sensory lead is surgically positioned in the chest, connected to the first one; during sleep, the sensory lead senses the inspiration phase and consequently the stimulating device causes the hypoglossal nerve to protrude the tongue, reducing the degree of obstruction.

Impact on practice statement

Recognising and managing OSAS is essential in everyday clinical practice due to its high prevalence and strong association with cardiovascular, metabolic, and neurocognitive disorders. Early identification through targeted screening and timely referral for diagnostic evaluation can significantly reduce long-term morbidity. Integrating OSAS assessment into routine check-ups, especially for at-risk patients, empowers clinicians to improve outcomes through multidisciplinary collaboration and personalised treatment strategies.